1. Technical Field
The present invention relates to surface-emitting type semiconductor lasers and methods for manufacturing the same, optical switches and optical branching ratio variable elements.
2. Related Art
Surface-emitting type semiconductor lasers are semiconductor lasers which emit laser light in a direction perpendicular to a semiconductor substrate, easy to handle compared to conventional edge emitting semiconductor lasers, and have a circular irradiation pattern, such that application thereof to a variety of sensors and light sources for optical communications are expected. Further, surface-emitting type semiconductor lasers that are used as light sources for optical communications are expected to be used not only for intermediate and short distance optical communications but also as optical circuit elements for chip-to-chip and inner-chip communications.
Also, interference type switches that use directional couplers in a planar direction and the like are widely used in the field of optical circuits (i.e., PLC: planar lightwave circuit) (see, for example, Japanese Laid-open Patent Application HEI 6-51354). However, it is difficult to form directional couplers in an up-and-down direction (a direction perpendicular to a planar direction).
It is an object of the present invention to provide a surface-emitting type semiconductor laser that can change the ratio of outputs of laser beams emitted in upward and downward directions of a substrate, and a method for manufacturing the same. Also, it is another object of the present invention is to provide an optical switch that uses the surface-emitting type semiconductor laser described above. Also, it is still another object of the present invention to provide an optical branching ratio variable element that can change the ratio of outputs of laser beams emitted in upward and downward directions of a substrate.